Sprinkler systems have for many years been used to dampen and/or to extinguish fire in different spaces, e.g. in offices, industrial premises, hotels, apartments or shops etc. A sprinkler system in most cases comprises a piping network or the like extending through the space that the sprinkler system is to protect in case of fire. The piping network is in most cases connected to a pressurized water supply and it may be divided into several branches, each of which may extend through different parts of the space concerned. In the various branches, one or more sprinkler heads are mounted. Each sprinkler head has a heat-sensitive triggering device. The triggering device is arranged to activate the sprinkler head if a fire breaks out near the sprinkler head. When the sprinkler head is activated, the sprinkler head spreads water from the piping network out over the fire and prevents it from spreading and/or ensures that it is extinguished.
There are two main categories of sprinkler systems, wet sprinkler systems and dry sprinkler systems. In an operative wet sprinkler system, there is pressurized water in the piping network both when the sprinkler system is in a non-activated state and when the sprinkler system is in an activated state. In an operative dry sprinkler system, there is no water or very little water in the piping network when the sprinkler system is in a non-activated state. Instead the piping network is supplied with water when a fire has been detected. Dry sprinkler system may advantageously be used in spaces exposed to large temperature variations. This is particularly appropriate if the sprinkler system run the risk of being exposed to cold that would freeze any possible water in the piping system and be able to burst the pipes resulting in leakage. Wet sprinkler systems are in other words typically used in spaces not running the risk of being exposed to cold that could freeze the water in the piping network.
In a wet sprinkler system water flow detectors may be used to detect when one or more sprinkler heads have been activated and spread water. One or more water flow detectors may be arranged in one or more branches of the piping system for detecting activation of one or more sprinkler heads in a branch. The activation of a sprinkler head usually indicates that a fire has broken out in a protected space and the space concerned should then be evacuated and fire department called. It is thus important to as safely as possible be able to detect that a sprinkler head has been activated, as it normally means that a fire has broken out.
Water flow detectors of now described and kind and the like thus have an important function in many wet sprinkler system and the water flow detectors should therefore be tested continuously to ensure that they from time to time work as intended.
It is also important that the water flow detectors of now described and kind and the like are reliable, i.e. that no or very few false alarms occur. One reason for false alarm is that air has gathered in one or more branches of the piping system in a wet sprinkler system. Because air may be compressed, the water in the piping system may begin moving without any sprinkler head having been activated. This may e.g. happen in spaces which are moving, e.g. in spaces on boats equipped with sprinkler systems, where rough sea may make the water in the piping system of the sprinkler system move, if air is gathered in one or more branches of the piping system. A water flow detector may detect such movements of the water and incorrectly indicate that a sprinkler head has been activated. It is thus important that any possible air may be removed from different branches of the piping system of a wet sprinkler system.
On the whole, it is advantageous if the function of a sprinkler system in whole or in part may be tested in a simple and quick way in different branches of the piping system of the sprinkler system.